This invention is an endoluminal prosthesis to be used in passageways or conduits of the human body, such as to restore the passage in blood vessels that have been narrowed or blocked by diseases such as a stenosis.
The present endoluminal prosthesis is particularly suitable for use in the vicinity of a bifurcation, mainly of the carotid artery.
The present invention also relates to that type of endoluminal prostheses which are self-expanding, such as those made of superelastic or shape memory material, such as Nitinol.
The present invention also relates to endoluminal prostheses provided with means for enabling prompt location thereof, such as by means of radioscopy.
Endoluminal prosthesis, particularly of the self-expanding type, are known for example from U.S. Pat. Nos. 4,665,771, 4,665,905, 4,925,445, EP-A-0928606, or WO 2005/104991.
Though being acceptable in many respects, particularly for their great flexibility and resilience, which enable them to be easily positioned in narrow and tortuous passages in their collapsed state, these endoluminal prostheses, in some cases, are not sufficiently suitable, when expanded, to support the vessel walls, in order to maintain a proper free lumen for the blood to pass therethrough.
Furthermore, in some cases the complex geometry of such known stents may be harmful, since it can hang up on or pinch the vessel wall, thus favoring the re-forming of obstructions, such as plaques and stenosis.
Particularly, in the carotid, the endoluminal prosthesis must ensure a considerable radial strength in the middle portion thereof, or generally in the portion positioned at the stenosis. Furthermore, the endoluminal prosthesis must be made with the least amount of material as possible, mainly in the end portions, or generally in those portions that are positioned outside the stenosis. In fact, it has been estimated that the ratio of the metal and the artery must remain within well defined limits, about 15%. Too high values lead to restenosis and high mechanical rigidity.